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PRELIMINARY
XRT79L71
498
REV. P2.0.0
1-CHANNEL DS3/E3 CLEAR-CHANNEL FRAMERLIU COMBO - CC/HDLC ARCHITECTURE
The purpose of the Transmit E3 Framer block is to accept data from the Transmit Payload Data Input Interface
block, the Transmit LAPD Controller, the Transmit Trail-Trace Message Controller block, and the Transmit SSM
Controller block, and to create an E3 data-stream. Afterwards, the Transmit E3 Framer block will route this E3
data-stream to the Transmit E3 LIU Block for transmission to the remote terminal equipment. The Transmit E3
Framer block also supports the following functions.
Transmitting the LOS Pattern (under Software control)
Transmitting the AIS Pattern (under Software control)
Transmitting the FERF (RDI) indicator (automatically and under software control)
Transmitting the FEBE (REI) indicator (automatically and under software control).
6.2.6.1
TRANSMITTING THE LOS PATTERN
The Transmit DS3/E3 Framer block within the XRT79L71 permits the user to transmit the LOS (Loss of Signal)
pattern to the remote terminal equipment.
In this case, the Transmit E3 Framer block will generate and
transmit an "All Zeros" pattern to the remote terminal equipment. The procedure for transmitting the LOS
Pattern is presented below.
Transmitting the LOS Pattern
The user can configure the Transmit DS3/E3 Framer block to transmit an LOS pattern by transmitting an "All
Zeros" pattern.
This can be accomplished by setting Bit 1 (TxLOS Enable) within the Transmit E3
Configuration Register - G.832" to "1" as depicted below.
FIGURE 232. ILLUSTRATION OF THE FUNCTIONAL BLOCK DIAGRAM OF THE TRANSMIT DIRECTION CIRCUITRY, WHEN-
EVER THE
XRT79L71 HAS BEEN CONFIGURED TO OPERATE IN THE E3, ITU-T G.832 CLEAR-CHANNEL FRAMER
MODE (WITH THE TRANSMIT DS3/E3 FRAMER BLOCK HIGHLIGHTED)
Transmit
Payload Data
Input
Interface
Block
Transmit
Payload Data
Input
Interface
Block
Transmit
DS3/E3
Framer
Block
Transmit
DS3/E3
Framer
Block
Transmit
DS3/E3
LIU Block
Transmit
DS3/E3
LIU Block
TxSer
TxNib[3:0]
TxInClk
TRING
TTIP
Transmit
Overhead Data
Input Interface
Block
Transmit
Overhead Data
Input Interface
Block
TxOHClk
TxOHIns
TxOHInd
TxOH
TxOHEnable
TxOHFrame
TxNibClk
TxFrame
Tx LAPD
Controller
Block
Tx LAPD
Controller
Block
From Microprocessor
Interface Block
Tx LAPD
Buffer
(90 Bytes)
Tx LAPD
Buffer
(90 Bytes)
Tx TTM
Controller
Block
Tx TTM
Controller
Block
Tx SSM
Controller
Block
Tx SSM
Controller
Block